Issue No. 11 February 2006 www.hkbiodiversity.net Feature Article Contents page Mist Net Survey of Bats with Feature Article : Three New Bat Species Records Mist Net Survey of Bats with Three New for Hong Kong Bat Species Records for Hong Kong 1 Working Group Column : Chung-tong Shek and Cynthia S.M. Chan Survey on the Short-nosed Fruit Bat Mammal Working Group (Cynopterus sphinx 短吻果蝠) in the Urban Areas of Hong Kong 8 漁農自然護理署哺乳動物工作小組在2003-05年之間進行了一項 蝙蝠霧網調查，目的為了解香港的非穴棲性蝙蝠的相對數目和分布， Wrinkle-lipped Free-tailed Bat 並評估其現有狀況和其生態價值。評估的結果是，在十個非穴棲性蝙 (Chaerephon plicata 皺唇犬吻蝠) 蝠品種之中，灰伏翼、褐扁顱蝠、喜山鼠耳蝠和一隻尚未確認的伏翼 in Hong Kong 11 蝠被列為可優先考慮加強保育的稀有及分布狹窄的蝙蝠品種。 Rare Species Highlight: White-browed Keelback (白眉游蛇) 12 Introduction Division Column : Bats comprise an important part of Hong Kong’s mammal fauna, making up over 50% of all local mammal species. They The Olive Ridley (Lepidochelys olivacea) are important components of our biodiversity and their small size, – an Unusual Sea Turtle Recorded in mobility and longevity combine to make them suitable indicator Hong Kong 13 species of general environmental conditions (Fenton, 1999). Bats Wetland Restoration Trial in Lions roost in special environments like caves and trees, and most of them are capable of echolocation. Different species may differ in Nature Education Centre, Tsiu Hang their susceptibility to the available survey or capture techniques, Special Area 14 and it is necessary to use several sampling methods to generate as complete a species list as possible. Contribution to the Hong Kong Biodiversity Three different kinds of survey methods are being used by the Do you have any views, findings and Mammal Working Group of Agriculture, Fisheries and Conservation observations to share with your colleagues Department (AFCD) for studying bats in Hong Kong: direct roost on the Biodiversity Survey programme? censuses at their roost sites, capture study using mist netting (Fig. 1) and harp trapping, and detection of echolocation calls. Please prepare your articles in MS Word format and send as attachment files by email to the Article Editor. Subscribing Hong Kong Biodiversity If you would like to have a copy, or if you know anyone (either within or outside AFCD) who is interested in receiving a copy of this newsletter, please send the name, organization, and email and postal addresses to the Article Editor. Chief Editor: P.M. So ([email protected]) Article Editor: K.Y. Yang ([email protected]) Fig 1. A researcher removing a Japanese Pipistrelle © All rights reserved. (Pipistrellus abramus 東亞家蝠) from a mist net. 2 Direct roost censuses are the best way to study For this analysis, all species found during the the cave-dwelling species, and based on the results, roosting cave censuses were excluded from the study. Horsfield’s Bat (Myotis horsfieldi 霍氏鼠耳蝠) was ranked The status of each species was classified following Shek as a species of conservation concern in Hong Kong and Chan (2005). (Shek and Chan, 2005). However, only 14 species of the Hong Kong bat species are known to roost in caves and Results the remaining roost in other habitats, such as buildings, At least 18 species of 300 individuals were caught in trees or rock crevices. Such non-cave-dwelling species 1,593 Net Meter Nights during the survey of 2003-05. The need other survey methods to study their distribution and status of ten non-cave-dwelling species is shown in Table status in Hong Kong. 1. Among these, the Short-nosed Fruit Bat (Cynopterus This survey employed mist nets to study non-cave- sphinx 短吻果蝠) and the Japanese Pipistrelle dwelling species. The mist net is the most effective (Pipistrellus abramus 東亞家蝠) were the most abundant way to capture flying bats and is the best way to study and widely distributed species respectively. In addition these species, which are not found during roosting cave to the Greater Bamboo Bat (Tylonycteris robustula censuses. 褐扁顱蝠) reported in the last issue (Shek and Chan, 2005), the identification of three more new bat species Methods found in Hong Kong has been confirmed. They are the Least Pipistrelle (Pipistrellus tenius 小伏翼), the Bats were caught by standard mist net methods Whiskered Myotis (Myotis muricola 喜山鼠耳蝠) and an (Kunz and Kurta, 1988), using 6, 12 or 18 meter nylon unidentified Pipistrelle sp.. These discoveries raised the mist nets (Avinet CH series mist nets). All nets were total number of bat species in Hong Kong to 26. After of 2.6 m in height, and nets may be used in double or comparing the relative abundance and distribution in triple high level by stacking two or three nets together Hong Kong, the Chinese Pipistrelle (Hypsugo pulveratus at the sub-canopy level. Nets were set over streams 灰伏翼), the Whiskered Myotis, the Greater Bamboo Bat and pools, along forest edges, in clearings, forest paths and the unidentified Pipistrelle sp. were ranked as rare or and other sites where bats were observed or that could species of conservation concern. otherwise serve as potential flight paths. The abundance of individuals captured were presented as individuals Discussion captured per meter of mist net employed per night. The mist net survey provides baseline information Site selection was aimed at covering all major on the abundance and distribution of ten species of countryside areas throughout Hong Kong, including non-cave-dwelling bats in Hong Kong. Four of them are Country Parks, Special Areas, and other countryside ranked either very common or common in this study, areas (Fig. 2). The distribution of bat species was including the Lesser Bamboo Bat, which was thought to analyzed by using the Hong Kong 1800 grid system, be rare in Hong Kong (Ades, 1999). in which species found in the same grid were pooled together for distribution analysis. Among these non-cave-dwelling species, five species were reported to roost in buildings or man-made structures, and some, e.g. the Japanese Pipistrelle, were found to roost in various types of man-made structures, such as under bridges, attics of houses, crevices in walls, or even air-conditioners. Such species are expected to be more widely distributed than other non- cave-dwelling species. Although some species roost in tree or bamboo, the Short-nosed Fruit Bat is widely found and commonly distributed at lower elevations in the urban areas, including parks and gardens, where human disturbance is omnipresent. It roosts under the modified fronds of the Chinese Fan-palm and Petticoat Palm in urban areas (Chan and Shek, 2006). Whereas the Lesser Bamboo Bat, which lives inside the hollow cavities of fresh bamboos such as the Tender Shoot Bamboo and Chinese Thorny Bamboo and can always Fig 2. Sites of mist net survey by AFCD in 2003-05. be trapped near bushes of these bamboo species, is Captured bats were held individually in cloth bags very common, the Greater Bamboo Bat is rare and highly and identified following Shek (2004 & 2005). Voucher restricted in Hong Kong. Its rarity and restrictedness may specimens were taken to confirm the identification of new be explained by its low frequency echolocation calls, or uncertain records, most of which were deposited with which are not effective in the cluttered space of bamboo the collection of the Biodiversity Conservation Division of bushes. the AFCD. 3 Mist nets are the most common device for capture flying bats, but many species, such as rhinolophid and hipposiderid bats, are highly maneuverable in flight and capable of echolocations; as a consequence, they are adept at avoiding mist nets. Furthermore, some species forage above the canopy level, and it is impossible to catch them by mist nets. It is recommended that mist net surveys are combined with acoustic monitoring by special bat detectors. The list of bat species recorded in Hong Kong is now 26 (Shek and Chan, 2005b). Four species new to Hong Kong were discovered during this study and it is anticipated that more species are awaiting our discovery. Species Account Japanese Pipistrelle 東亞家蝠 – Very common Pipistrellus abramus (Temminck, 1840) (Fig. 3) The Japanese Pipistrelle is considered the most common bat species found in both the countryside and urban areas of Hong Kong. It roosts in various types of buildings and other man-made structures, such as the attics of older buildings or even in fans or air-conditioners. It is also found to be the most abundant species in wetland areas, such as Mai Po Nature Reserve and the Hong Kong Wetland Park in Tin Shui Wai (Fig. 4). Fig 3. Japanese Pipistrelle (Pipistrellus abramus 東亞家蝠) Fig 4. Records of the Japanese Pipistrelle in Hong Kong (2003-05). Short-nosed Fruit Bat 短吻果蝠 – Very common Cynopterus sphinx (Vahl, 1797) (Fig. 5) The Short-nosed Fruit Bat lives in a wide variety of habitats, ranging from woodlands to lowlands and hills, and it is also recorded in urban areas (Fig. 6). It roosts in trees with dense clumps of leaves, under palm fronds or occasionally under the roof of a house. It is the only bat species in Hong Kong that constructs its own roosts by chewing the veins of the large fan-shaped leaves of the Chinese Fan-palm and Petticoat Palm. The colony size ranges from one to 30 individuals, and apparently a harem-type arrangement exists (Chan and Shek, 2006). Fig 5. Short-nosed Fruit Bat (Cynopterus sphinx 短吻果蝠) Fig 6. Records of the Short-nosed Fruit Bat in Hong Kong (2003-05). 4 Lesser Bamboo Bat 扁顱蝠 – Very common Tylonycteris pachypus (Temminck, 1840) (Fig. 7) The Lesser Bamboo Bat is remarkably adept at gaining access to and roosting in the internodes or hollow joints of thick and fresh bamboo stems, such as the Tender Shoot Bamboo and Chinese Thorny Bamboo in Hong Kong (Fig.